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RE: Population PKPD using hair drug concentration

From: Joachim Grevel <jgrevel>
Date: Fri, 12 Jun 2015 15:48:07 +0100

Dear Leonid and Bernard,
Why not treat hair like a urine compartment that is not emptied until =
the hair is pulled out with the root? NONMEM user guides contain all you =
need to model a "collection compartment" like urine/hair.

Have fun,


Joachim Grevel, PhD
Scientific Director
BAST Inc Limited
Loughborough Innovation Centre
Charnwood Building
Holywell Park, Ashby Road
Loughborough, LE11 3AQ
Tel: +44 (0)1509 222908

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-----Original Message-----
From: owner-nmusers
On Behalf Of Leonid Gibiansky
Sent: 12 June 2015 14:55
To: Bernard Ngara; nmusers
Subject: Re: [NMusers] Population PKPD using hair drug concentration

Dear Bernard,

This looks like really interesting problem. Based on the idea that it =
should be a long delay, I would start with the transit compartment model =
(you can google for the references on this type of models) with the =
input from the plasma compartment. The last compartment will represent a =
barber shop. The number of transit compartment can be increased until =
you get a sufficiently long delay. Observation compartment can be either =
the last one, or the sum of several, depending on how measurements are =
done (at a particular hair length, or by grinding the hair together =
before measurement). Depending on whether hair can eliminate the drug =
(or it happens only in the barber shop), hair clearance can be assigned =
to all or only to the last of those transit compartments.

It could be that a simple effect compartment model with a very slow ke0 =
could describe it as well but you should be able to see it by increasing =
or decreasing the number of transit compartments.


Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
e-mail: LGibiansky at
tel: (301) 767 5566

On 6/12/2015 8:56 AM, Bernard Ngara wrote:
> Dear all
> I am a working on a study that measures both short and long term
> exposure to drug using plasma and hair drug concentration. What
> methods can I use to model hair drug concentration. You can give
> references so that I can read.
> Thanks once again.
> Regards
Received on Fri Jun 12 2015 - 10:48:07 EDT

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